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What is Biological Diversity?

What is Biological Diversity?. The Delhi Sands Flower-Loving Fly: First fly on the Federal Endangered Species List!. What is Biological Diversity?. 1) Species diversity Includes all organisms on planet Provides resources for humans. What is Biological Diversity?. 2) Genetic diversity

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What is Biological Diversity?

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  1. What is Biological Diversity? • The Delhi Sands Flower-Loving Fly: First fly on the Federal Endangered Species List!

  2. What is Biological Diversity? • 1) Species diversity • Includes all organisms on planet • Provides resources for humans

  3. What is Biological Diversity? • 2) Genetic diversity • Allows species to survive and adapt through time

  4. What is Biological Diversity? • 3) Community diversity • Supports proper ecosystem functioning • Provides human benefits: ecological services (filter water/air, flood/erosion control, etc.).

  5. Species diversity: what is a species? • Morphological def’n: Group of individuals that is morphologically, physiologically, biochemically different from other groups • Biological def’n: Group of individuals which can interbreed to produce fertile offspring • Practical def’n: Whatever a competent taxonomist says it is!

  6. Why does taxonomy matter? • Degree of uniqueness can be conservation criterion • With limited resources, shouldn’t we save the most unique organisms? • True for all taxonomic levels (see Box 2 for review of these) • So, should we emphasize species, genera, families……..?

  7. Importance of species def’n: the case of the red wolf • Described as species separate from gray wolf

  8. Importance of species def’n: the case of the red wolf • Range: southeastern U.S. • Predator control programs decimated red wolf pop’ns

  9. Importance of species def’ns: the case of the red wolf • Listed as Endangered in 1967 • Captive breeding started 1973 • Millions of $ spent to date on breeding and reintroduction program of “pure” red wolves.

  10. Importance of species def’ns: the case of the red wolf • Problem: 1994 genetic study suggested red wolf was hybrid between gray wolf and coyote. Who am I??

  11. Species and the dangers of hybridization • Hybrids: fertile offspring of 2 taxonomic species • Introgression: transfer of genes between species via hybrids • Hybridization can erode species identity through introgression.

  12. Hybridization examples: Ethiopian Wolf • Critically endangered • Mates with wild domestic dogs • Erodes genetic identity of wolf • “Genetic assimilation”

  13. Hybridization examples: Hawaiian duck • Hawaiian duck only found there (separate species) • Endangered species • Problem: introduced mallards interbreed Hawaiian duck Mallard

  14. Hybridization examples: Lantana depressa • Found only in Dade County FL

  15. Hybridization examples: Lantana depressa • Hybridizes with Lantana camara • Introduced shrub common in southern gardens • Hybrids are spreading, as are Lantana camara genes thru cross pollination. Lantana camara

  16. Can hybridization save rare organisms? • Example: Florida panther • Population of 50-70 pumas or cougars • One of 30 subspecies described • Suffers from low genetic diversity.

  17. Can hybridization save rare organisms? • Several Texas pumas introduced in 1995 to add new genes to population • Seems to be boosting numbers • Question: • Will this erode conservation status of Florida panther? • Now has 18-22% Texas genes!.

  18. How do new species arise? • Divergent evolution: Breeding barriers allow populations to evolve independently

  19. Divergent evolution: Kaibab Squirrels • Grand Canyon separates Kaibab plateau from Coconino plateau

  20. Divergent evolution: Kaibab Squirrels • Different squirrel species on each side of canyon Kaibab squirrel Abert Squirrel

  21. How do new species arise? • Divergent evolution: Barrier to breeding allows populations to evolve independently • Adaptive radiation: Rapid speciation when new habitats colonized (common on islands)

  22. Adaptive radiation: Madagascar lemurs • About 30 living and 10 extinct species • From common ancestor to island (60 mya)

  23. Madagascar lemurs • About 30 living and 10 extinct species Ring-tailed lemur Aye-aye Black and white ruffed lemur

  24. Adaptive radiations: Hawaii • Drosophila Fruit flies: 500 species! 8 mya Silverswords: 3 genera (about 30 species) 8 mya

  25. Adaptive radiations: Hawaii • Honeycreepers • About 16 species Iiwi Crested honeycreeper

  26. Problem: Rate of evolution slow • Current extinction rate 100-1000 times that of speciation rate • And slowing! • 1) Fewer populations left to evolve • 2) Protected areas too small for some groups to evolve in (see Fig. 2.4) • 3) Some threatened species are last members of very distinct lineages (these arise even more slowly than species do).

  27. Measuring species diversity • Species richness: number of species present • Also called alpha diversity • Species diversity: combination of richness and evenness • Evenness: how numbers of individuals are spread among species • Diversity indices: math approaches • Example: Shannon index

  28. Measuring species diversity • Other diversity concepts • Gamma diversity: regional count of species • Beta diversity: rate of change of species richness from community to community within region • Beta links alpha and gamma diversity

  29. Alpha=species/mtn Gamma=species/region Beta=gamma/alpha Example Alpha Gamma Beta Region 1 C 1.2 C D 5 6 D C D B B B E E E A A F Region 2 2.5 2 5 C D D E B A Region 3 6 3.0 2 E B D C A F

  30. What is genetic diversity? Terms • Gene: basic unit of heredity (expressed as phenotype) • Allele: • Locus (plural: loci): • Heterozygote • Homozygote

  31. What is genetic diversity? Terms • Gene: • Allele: alternate forms of a gene • Locus (plural: loci): • Heterozygote • Homozygote

  32. What is genetic diversity? Terms • Gene: • Allele: • Locus (plural: loci): a position or place on a chromosome • Heterozygote: • Homozygote

  33. What is genetic diversity? Terms • Gene: • Allele: • Locus (plural: loci): • Heterozygote: an individual possessing two different alleles for a given locus (e.g., Aa) • Homozygote

  34. What is genetic diversity? Terms • Gene: • Allele: • Locus (plural: loci): • Heterozygote: • Homozygote: an individual possessing identical alleles at a given locus (e.g., AA or aa)

  35. What is genetic diversity? Terms • Heterozygosity (H): • A measure of genetic variation within a population • High H generally good • Masks harmful alleles • Allele variation allows flexible response to environmental challenges • H can be estimated with molecular methods.

  36. Measuring genetic diversity • Allozymes: phenotypes in the form of proteins (e.g. enyzmes) are used to detect genotypic differences • RFLP: • Molecular markers: • Mitochondrial DNA (mtDNA):

  37. Measuring genetic diversity • Allozymes: • RFLP: direct examination of differences in DNA sequence length using restriction enzymes • Molecular markers: • Mitochondrial DNA (mtDNA):

  38. Measuring genetic diversity • Allozymes: • RFLP: • Molecular markers: direct examination of molecular “alleles” (e.g. microsatellites) • Mitochondrial DNA (mtDNA):

  39. Measuring genetic diversity • Allozymes: • RFLP: • Molecular markers: • Mitochondrial DNA (mtDNA): compare sequences between and among populations

  40. Calculating H • Score individuals as homozygous or heterozygous at several loci • Calculate hj= proportion of heterozygous loci per individual • Average across many individuals = H

  41. Measurement of H in vertebrates • Allozyme data (n=648 species) • From Avise (1994)

  42. Examples of H • Northern Elephant Seal • 30 individuals in 1900 Man, am I lonely or what??

  43. Examples of H • Northern Elephant Seal • 30 individuals in 1900 • Now 50,000+ • Conservation success story That’s better!!

  44. Examples of H • Northern Elephant Seal • Problem: Little genetic diversity! • 55 allozyme loci: H=0

  45. Examples of H • Cheetah • Allozyme study: 155 proteins • H=0.013 • Genetic similarity so great, skin grafts between cats accepted as “own” skin!

  46. Community diversity: affected by species interactions • Competition: Review ecology notes! • Predation: Review ecology notes! • Mutualism: Review ecology notes! • Symbiosis: Review ecology notes!

  47. Communities: organized into trophic levels • Primary producers: Review ecology notes! • Primary consumers: Review ecology notes! • Secondary consumers: Review ecology notes! • Parasites/pathogens: Review ecology notes! • Decomposers/detritivores: Review ecology notes!

  48. Keystone species/guilds • Guild: group of species with a similar ecological function in a community • Ex, frugivorous (fruit-eating birds) • Ex, grazing mammals • Keystone: species or guild that affects community more than expected based upon its abundance/biomass (disproportionate impact)

  49. The Keystone Concept Keystone Dominant Relativeimpact of species/guild Common but low impact Rare species Relative biomass

  50. Keystone examples: sea otters • Hunted almost to extinction on West Coast • Now expanding back • Top carnivores (almost): eat mussels, abalone, sea urchins

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